Question: Khan.scratchpad.disable(); To move up to the maestro level in his piano school, Kevin needs to master at least $156$ songs. Kevin has already mastered $31$ songs. If Kevin can master $7$ songs per month, what is the minimum number of months it will take him to move to the maestro level?
Answer: To solve this, let's set up an expression to show how many songs Kevin will have mastered after each month. Number of songs mastered $=$ $ $ Months at school $\times$ Songs mastered per month $+$ Songs already mastered Since Kevin Needs to have at least $156$ songs mastered to move to maestro level, we can set up an inequality to find the number of months needed. Number of songs mastered $\geq 156$ Months at school $\times$ Songs mastered per month $ +$ Songs already mastered $\geq 156$ We are solving for the months spent at school, so let the number of months be represented by the variable $x$ We can now plug in: $x \cdot 7 + 31 \geq 156$ $ x \cdot 7 \geq 156 - 31 $ $ x \cdot 7 \geq 125 $ $x \geq \dfrac{125}{7} \approx 17.86$ Since we only care about whole months that Kevin has spent working, we round $17.86$ up to $18$ Kevin must work for at least 18 months.